In recent years, Wi-Fi Direct has attracted attention as a terminal-to-terminal communication scheme in view of broader bandwidth, increased security, and the like. While conventional Wi-Fi networks work in the infrastructural mode with a specific device serving as an access point (AP), Wi-Fi Direct-compliant networks enable communication to be performed within a group, with any peer-to-peer (hereinafter, abbreviated as “P2P”) terminal, not a specific device, serving as a group owner (NPL 1). A group owner is a P2P terminal that operates as an access point of a group and, as the parent of that group, can form the group including other P2P terminals as clients.
To form a group between Wi-Fi Direct-compliant P2P terminals, first, it is necessary to search for a P2P terminal in vicinity through Device Discovery processing as described below. In Device Discovery processing, each terminal alternately repeats Search state and Listen state and, in Search state, sends out Probe Request while sequentially changing predetermined channels and waits for Probe Response thereto. In Listen state, each terminal waits for Probe Request from another terminal and, when receiving Probe Request, returns Probe Response thereto. A terminal can discover another terminal by receiving Probe Response in this manner.
Then, when P2P terminals are discovered, they connect to each other through GO Negotiation processing, with one of them becoming the group owner (GO) and the other becoming a client, and subsequently sequentially perform WPS Provision Phase-1 (authentication phase) and Phase-2 (encryption phase), whereby a group is formed.
Within a P2P group formed as described above, terminals can share data and transfer data at high speed without connecting to the Internet or the like. Wi-Fi Direct, in particular, supports a robust security protocol and therefore can realize a higher level of security than the conventional ad-hoc mode (IBSS: Independent Basic Service Set and the like).